Sheet glass is normally produced by continuously supplying molten glass to an apparatus, and downdrawing the molten glass from the apparatus in the shape of a strip to allow the molten glass to cool and solidify. Disk rolls, which function as a pair of tensile rolls, are used to hold and downdraw the molten glass.
A plurality of ring-shaped disk materials cut from a millboard (sheet-shaped product or base material) are normally attached (fitted) to a shaft (rotary axis) to obtain a roll-shaped stack. The roll-shaped stack is pressed and secured from both ends via a flange. The outer circumferential surface of the disk materials serves as a molten glass transfer surface.
The disk roll that transfers strip-shaped molten glass is required to exhibit heat resistance, flexibility, and hardness, and not to damage the surface of glass. For example, a disk roll that contains heat-resistant inorganic wool, mica, and clay has been known (see JP-T-2010-510956, JP-A-2009-132619, and JP-A-2004-299980).
A disk roll is normally produced by a suction-dehydration molding method or a papermaking method using an aqueous slurry depending on the drainage. The papermaking method can produce a large sheet with good efficiency, but requires high drainage.